Interrelationships and functions of the pyruvate kinase isozymes and their variant forms: a review.

The relationships among and the properties of the pyruvate kinase isozymes are reviewed, emphasizing their potential role in carcinogenesis. Particular consideration is given to evaluation of the concept that the three major nonreadily interconvertible forms are the products of distinct genes, the relationship of these forms to additional separable forms of pyruvate kinase, the types and possible functions of interconvertible forms of the major isozymes, and mechanisms affecting the genetic expression of the isozymes. Emphasis is placed upon the apparent derepression of the fetal isozyme in hepatomas and the influence of neoplasms and their extracts on the expression of pyruvate kinase in the liver of host animals.